辽宁省城市老燃气管网改造的必要性与措施

以辽宁省为例,探讨了我国城市老燃气管网改造的必要性、存在的问题及改造措施。     

Indoor air pollution and its impact on children under five years old in Bangladesh

Indoor air concentrations of volatile organic compounds (VOCs), carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), and dust particles were measured for 49 biomass and 46 fossil fuel users in urban slums of Dhaka, Bangladesh. The health impacts of these pollutants were assessed on 65 and 51 children under five years old from families who use biomass and fossil fuel as main source of energy, respectively. Mean concentrations of CO were found to be significantly higher in biomass fuel users (P = 0.010), while geometric mean concentrations of benzene, xylene, toluene, hexane, total VOCs, and NO2 were significantly higher (P < 0.01) in the fossil fuel users. Symptoms such as redness of eyes, itching of skin, nasal discharge, cough, shortness of breath, chest tightness, wheezing, or whistling chest were found to be associated with the choice of biomass fuel, with the odds ratio ranging from 4.0 to 6.3. No significant association of use of biomass fuel with respiratory diseases, eczema, diarrhea, or viral fever was observed after adjustment for potential confounders. These results suggest a significant association between the biomass fuel-using population and respiratory symptoms. These symptoms may not be due to the pollutants only, as some other underlying causes may be present. PRACTICAL IMPLICATIONS: The health of children under five years old in Bangladesh, especially those living in poor socioeconomic conditions, is considered to be worsening because of indoor air pollution. It is commonly suggested that biomass fuel should be replaced by fossil fuel, as pollution levels are believed to be higher with biomass fuel. Our findings, however, suggest that pollution can be higher with fossil fuels, and indicate that a switch in fuel from biomass to fossil does not necessarily improve the children's health. Awareness programs should therefore be undertaken to avoid the unnecessary use of gas. Clean fuels and clean stoves should also be ensured to reduce emissions of indoor air pollutants.     

掺加微粉对高钛重矿渣砂浆性能的影响

通过对掺加不同含量的渣粉和粉煤灰在高钛重矿渣砂浆中的试验研究，验证了高钛重矿渣砂浆中适量的双掺矿渣微粉、粉煤灰可以改善砂浆拌合物的强度与和易性，满足砌体施工规范要求。     

浅谈城市街道空间

通过对城市街道空间的分析,指出在新的城市建设发展中破坏了旧城区的空间形态等问题。并且针对北京旧城区的现状,对街道空间的尺度设计初步提出了切实可行的建议。     

传统街区改造中的"渐进更新"策略与低成本建造技术--以"重庆川道拐"街区为例

通过4年多的"渐进更新"和低成本的旧建筑再利用,一个典型的传统山地街区在延续原有城市肌理同时创造了新的城市景观和就业岗位.街区的更新模式与建筑策略有别于普遍的"大拆大建"做法,是旧城改造新模式的探索.文中强调渐进更新和旧建筑再利用是"政府引导"、"群众动员"与"规划设计"共同作用的良性结果,并分析了规划设计与实践的方法、手段、取得的成果与存在的问题.街区今天依然处于持续更新之中.     

用单螺杆挤出机制备缓凝砂浆包裹钢筋的研究

用单螺杆挤出机实现了缓凝砂浆连续包裹预应力钢绞线.基于缓凝砂浆的动力学性质,建立了缓凝砂浆螺旋输送模型;研究了缓凝砂浆在单螺杆挤出机中的流动情况.结果表明,当螺杆转速为122~220 r/min时,缓凝砂浆可实现连续输送、挤出和包裹;用单螺杆挤出机可得到包裹缓凝砂浆并外覆塑料护套的预应力钢绞线.     

外墙外保温干粉黏接剂粘结性能的研究

用正交试验法确定了外墙外保温干粉黏接剂中各种材料的最佳配合比.     

干混特细砂陶瓷墙地砖粘结砂浆研究

采用保水剂、粘结剂改性,可配制施工性、粘结性、耐候性良好的特细砂瓷砖粘结砂浆。它的抗流挂性好,滑移量小于2 mm,有较充分的凉置时间,凉置20 min的粘结强度大于1.0 MPa,可满足瓷砖粘贴薄层施工的要求。采用聚丙烯纤维复合改性,可配制抗裂性较好的柔性瓷砖粘结砂浆。介绍这种新型粘结砂浆的配制原理、方法和性能。     

水泥砂浆塑性收缩开裂试验条件的研究

研究了约束状况，失水条件及试件厚度等因素对水泥砂浆塑性收缩开裂性能的影响。结果表明：（1）增加钢筋框中部约束或取消钢筋框均可减少砂浆塑性收缩开裂性能；底部凹凸状约束及面层铺设钢丝网可使砂浆塑性开裂有所减小，但不能消除塑性开裂现象；基本去除约束的准自由状态可使砂浆免除塑性收缩开裂。（2）失水条件对砂浆塑性收缩开裂有明显影响，灯与电网扇同时开启所形成的“风吹日晒”比单纯“风吹”、“日晒”更易于使砂浆塑性收缩开裂；加强抹面处理可使塑性收缩开裂减小，维持较长时间的洒水养护可消除塑性开裂现象。（3）增加试件厚度可减少砂浆的塑性收缩开裂，混凝土的抗塑性收缩开裂能力比砂浆强。     

混凝土小砌块墙体渗漏试验

利用幕墙动风压试验设备,成功模拟自然界风雨对墙体的作用,将4种砌块和5种砂浆进行组合对比,形成20个试验模块,同时接受风雨测试,得出了国内首例砌块墙体渗漏数据,为今后相关研究起铺垫和参考作用。